This invention relates to portable electric routing tools and, more particularly, to a depth of cut adjustment mechanism for such a tool.
In U.S. patent application Ser. No. 07/661,619, filed Feb. 28, 1991, now U.S. Pat. No. 5,074,724, and assigned to the assignee of the present invention, the contents of which are hereby incorporated by reference, there is disclosed a portable electric router having a depth of cut adjustment mechanism including an adjustment ring which engages a screw thread on the motor housing and rotationally engages the router base. The motor housing and base are prevented from having relative rotation therebetween. The rotational engagement of the router base by the adjustment ring is effected by providing the base with an external annular groove and providing the adjustment ring with a projection engaging the groove so that the adjustment ring is rotatable on the base about the longitudinal axis of the router. The adjustment ring is preferably formed as a unitary molded plastic member which comprises two hingedly joined substantially semi-cylindrical portions. When the router base is made of a material similar to the material of the adjustment ring, the adjustment ring rotates on the base in a relatively frictionless manner and is not subject to excessive wear. However, if the router base is formed of metal, frictional forces are generated between the projection of the adjustment ring and the walls of the annular groove of the base. These frictional forces detract from the free relative rotation of the adjustment ring. Further, the projection on the adjustment ring is subjected to excessive wear. Accordingly, it is an object of this invention to provide an arrangement in a router of the type described which allows for a relatively frictionless engagement between the adjustment ring and the router base when the router base is formed of metal and the adjustment ring is formed of plastic.